合理运用谨慎性原则,提供真实可靠会计信息

阐述谨慎性原则运用中存在的两面性,并针对谨慎性原则与其他会计原则的矛盾和可操作性弱的缺点提出一些改进方法.     

Provably secure RSA‐type signature based on conic curve

In electronic communication and wireless communication, message authentication should be necessary. However, traditional method message authentication code (MAC) employs a symmetric cryptographical technique and it needs to keep a shared private key between two parties. For convenience, people now begins to use public key techniques to provide message authentication. In wireless communication, we shall save more space for message itself because of the limited resources. Therefore, we believe that our proposed digital signature scheme will be more fitful for this kind of communication due to the following merits: (1) in addition to inheriting the merits of RSA signature such as high verification efficiency, the proposed scheme also shows its advantage over RSA by resisting low public key exponent attack; (2) comparing with 1024 bits RSA, our digital signature scheme can sign 2048‐bit long message once, and generate a signature with 1025 bits length which doubles the capacity of the 1024‐bit RSA signature; (3) the scheme is provably secure and its security is tightly related to the hardness of conic‐based (CB)‐RSA assumption. Copyright © 2008 John Wiley & Sons, Ltd.     

A quadratic approximation for structural topology optimization

In topology optimization, it is customary to use reciprocal‐like approximations, which result in monotonically decreasing approximate objective functions. In this paper, we demonstrate that efficient quadratic approximations for topology optimization can also be derived, if the approximate Hessian terms are chosen with care. To demonstrate this, we construct a dual SAO algorithm for topology optimization based on a strictly convex, diagonal quadratic approximation to the objective function. Although the approximation is purely quadratic, it does contain essential elements of reciprocal‐like approximations: for self‐adjoint problems, our approximation is identical to the quadratic or second‐order Taylor series approximation to the exponential approximation. We present both a single‐point and a two‐point variant of the new quadratic approximation. Copyright © 2009 John Wiley & Sons, Ltd.     

矿业遗迹保护风险内涵的二元特性分析

矿业遗迹保护的顺利进行是以科学的风险评价为保障的,而对风险进行适当、准确地描述和表达是保证风险评价科学性的基础和理论前提。风险的概念与项目的成功标准息息相关,本文对矿业遗迹的价值及利益相关者的预期效益进行了深入剖析,结合风险的基本内涵,从矿业遗迹资源多重价值和矿业遗迹保护项目效益函数分析入手,讨论矿业遗迹保护风险的内涵,明确矿业遗产保护风险内涵的二元特性。在此基础上,给出了矿业遗迹保护风险的确切定义。     

On the equivalence of optimality criterion and sequential approximate optimization methods in the classical topology layout problem

We study the ‘classical’ topology optimization problem, in which minimum compliance is sought, subject to linear constraints. Using a dual statement, we propose two separable and strictly convex subproblems for use in sequential approximate optimization (SAO) algorithms. Respectively, the subproblems use reciprocal and exponential intermediate variables in approximating the non‐linear compliance objective function. Any number of linear constraints (or linearly approximated constraints) are provided for. The relationships between the primal variables and the dual variables are found in analytical form. For the special case when only a single linear constraint on volume is present, we note that application of the ever‐popular optimality criterion (OC) method to the topology optimization problem, combined with arbitrary values for the heuristic numerical damping factor η proposed by Bendsøe, results in an updating scheme for the design variables that is identical to the application of a rudimentary dual SAO algorithm, in which the subproblems are based on exponential intermediate variables. What is more, we show that the popular choice for the damping factor η=0.5 is identical to the use of SAO with reciprocal intervening variables. Finally, computational experiments reveal that subproblems based on exponential intervening variables result in improved efficiency and accuracy, when compared to SAO subproblems based on reciprocal intermediate variables (and hence, the heuristic topology OC method hitherto used). This is attributed to the fact that a different exponent is computed for each design variable in the two‐point exponential approximation we have used, using gradient information at the previously visited point. Copyright © 2007 John Wiley & Sons, Ltd.     

一个改进的基于圆锥曲线的多重签名方案

通过对基于圆锥曲线上的数字签名和多重签名方案的分析,发现所提方案并不能满足相应的安全性.针对此问题,利用整数环Zn上圆锥曲线上的签名体制,提出了一个改进的在Zn圆锥曲线上的基于身份的多重签名方案.通过分析,改进的方案在大数分解和圆锥曲线上的离散对数双重困难问题下具有更好的安全性和不可伪造性.     

反求标准型有理二次Bezier曲线的参数与内权因子

给定不共线的三个控制顶点和位于这些项点的凸包内在二次曲线上的一点，可以决定一条标准型有理二次Ｂｅｚｉｅｒ曲线。本文提供了一些简单有效的方法，反求曲线上该点的参数和内权因子，避免了数值计算的不稳定性。     

三次加权Lupas q-Bezier曲线表示的圆锥曲线

为了研究三次加权Lupas q-Bezier曲线表示圆锥曲线,讨论了三次加权Lupas q-Bezier曲线是圆锥曲线的充要条件和分类情况.首先得到三次加权Lupas q-Bezier曲线退化成二次加权Lupas q-Bezier曲线的充要条件的,接着采用Wachspress坐标表示三次加权Lupas q-Bezier曲线,得到三次加权Lupas q-Bezier曲线是圆锥曲线的几个充要条件;进而得到三次加权Lupas q-Bezier曲线的形状不变因子,及其表示圆锥曲线的分类情况.特别地,通过引入Wachspress坐标,得到三次加权Lupas q-Bezier曲线表示圆锥曲线的本质几何条件.数值实验显示,用三次加权Lupas q-Bezier曲线表示的圆锥曲线可通过选择不同的形状参数来灵活地调整曲线的类型和形状.     

一致K-（Fb，ρ）-凸多目标半无限规划的Wolfe型对偶性

利用K-方向导数和K-次微分,定义了一致K-（Fb,ρ）-凸,一致K-（Fb,ρ）-伪凸和一致K-（Fb,ρ）-拟凸等一些非光滑非凸函数,并研究了涉及此类广义凸性的一类非光滑多目标半无限规划的Wolfe型对偶性．     

Nonhomogeneos Boundary-Value Problem for Semilinear Hyperbolic Equation. Stability

We discuss the solvability of the nonhomogeneous boundary-value problem for the semilinear equation of the vibrating string x _tt (t, y) − Δx(t, y) + f(t, y, x(t, y)) = 0 in a bounded domain and a certain type of superlinear nonlinearity. To this end, we deduce new dual variational method. Next, we discuss the stability of solutions with respect to the boundary control and initial conditions.